The Under Armour Men's HeatGear Long Sleeve Compression Shirt combine lightweight comfort, breathable performance, and easy mobility in a streamlined athletic design. HeatGear is our original performance baselayer-the one you put on first and take off last. So we made it extra comfortable by wicking sweat and stretching so you can move no matter what. Super-light HeatGear fabric delivers superior coverage without weighing you down Material composition includes Body: 84% Polyester/16% Elastane | Mesh: 92% Polyester/8% Elastane. Notable features include Mesh underarm & back panels for strategic ventilation; Material wicks sweat & dries really fast; Ergonomic design keeps seams off high abrasion areas & increases durability.